Journal articles: 'Optical code division multiple access (OCDMA)'

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Bouregaa, Mouweffeq, Mohammed El Kebir Chikh-Bled, Mohammed Debbal, Mohammed Chamse Eddine Ouadah, and Hicham Chikh-Bled. "Optical Code Division Multiple Access for FTTH system." Photonics Letters of Poland 10, no. 4 (December 31, 2018): 121. http://dx.doi.org/10.4302/plp.v10i4.861.

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Many multiple access techniques have been proposed and demonstrated to provide flexible solutions for FTTH network configurations. The performance of this system suffers because of the correlation properties that contribute to a high level of Multiple Access Interference (MAI), low system capacity (users), and lower transmission rate. In this paper, we have proposed Optical CDMA (OCDMA) as a configuration solution for FTTH networks to improve the performance of this type of network. Full Text: PDF References. Z. Mateusz, M. Mariusz, On cost of the uniformity in FTTH network design, Conference on Transparent Optical Networks (2017), 87-90 CrossRef CEDRIC F. LAM, Passive Optical Networks- Principles and Practice, first ed., British Library, USA, 2007. DirectLink M.K. Abdullah, W.T. P'ng, P.W. Lau, E.R. Tee, FTTH access network protection using a switch, Asia Pacific Conference on Communications (APCC), 3(2003) 1219–1222. CrossRef J. Ronnakorn, S. Napat, L. Somkiat, Design and implement of GPON-FTTH network for residential condominium, Conference on Computer Science and Software Engineering, (2017), 333-339. CrossRef M. BOUREGAA, M. CHIKH-BLED, Comparative Study of Optical Unipolar Codes for Incoherent DS-OCDMA system, International Journal of Hybrid Information Technology, 6 (2013) 225-236. CrossRef M. BOUREGAA, M. CHIKH-BLED, The performance of a DS-OCDMA system using Orthogonal Optical Codes (OOC), European Scientific Journal, 9 (2013), 322-335 CrossRef M. Iwase, Y. Ishikawa, T. Komatsu, J. Kasahara, N. Hattori, M. Miura, N. Nakamura, K. Odaka, Optical transceiver modules for gigabit Ethernet PON FTTH systems, Furukawa Review, 28 (2005) 8-10. DirectLink

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Wijanto, Eddy, and Chun-Ming Huang. "Design of Bipolar Optical Code-Division Multiple-Access Techniques Using Phase Modulator for Polarization Coding in Wireless Optical Communication." Applied Sciences 11, no. 13 (June 26, 2021): 5955. http://dx.doi.org/10.3390/app11135955.

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In this study, a bipolar optical code-division multiple-access (Bi-OCDMA) technique based on spectral amplitude coding (SAC) was proposed by using a phase modulator to realize polarization coding through a free-space optical (FSO) channel. Various types of noise, such as amplified spontaneous emission (ASE) noise, thermal noise, and shot noise, were included in the simulation to approach the real application. The first simulation, utilizing a modified M-sequence as signature code, demonstrated that the proposed Bi-OCDMA system could be implemented in FSO communication. The proposed Bi-OCDMA scheme improves the transmission rate and power efficiency compared with the previous scheme. The structure of the proposed system alleviates multiple-access interference (MAI) with a simple and cost-effective design. The second simulation observed the performance of the proposed Bi-OCDMA for two users with several well-known SAC codes, i.e., multi-diagonal (MD) code, modified quadratic congruence (MQC) code, modified maximum length sequence (M-sequence) code, and Walsh–Hadamard code, in extreme weather conditions, both for additive white Gaussian noise (AWGN) and turbulence-induced fading channel. The simulation results indicated that the Walsh–Hadamard code has superior performance compared to other codes. The results show the MD code can be implemented in the proposed Bi-OCDMA scheme for a medium-distance FSO.

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Nlend, Samuel, and Theo G. Swart. "Construction and Characterization of Optical Orthogonal Codes (n,w,1) for Fast Frequency Hopping-Optical Code Division Multiple Access." ECTI Transactions on Electrical Engineering, Electronics, and Communications 20, no. 1 (February 18, 2022): 62–73. http://dx.doi.org/10.37936/ecti-eec.2022201.246105.

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This paper investigates a new combinatorial construction approach based on cyclic difference packings for the construction of an optical orthogonal code that is suitable as a time spreading sequence for fast frequency hopping optical code division multiple access (OCDM) systems. The proposed construction provides a solution to the electrical decoding delay problem when compared to its optical counterpart, as well as other optimization issues. The criteria for optimizing the performance of such an OCDMA system are provided, namely: the flexibility and simplicity in constructing the optimal code for any length and weight, a reduction in the encoding/decoding complexity that complies with changes in the fast frequency hopping system, and the provision of system transfer transparency, a decoding rule that exploits the embedded asymmetric error correcting capability of the code. Our neighbor difference approach refers to the partition of different solutions into sub-classes, given in the correlation matrix form. It takes into account both direct and recursive combinatorial code construction methods, and the resulting characteristics are evaluated accordingly. A performance analysis based on the OCDMA channel is given, and a comparison with other difference family solutions is performed.

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Rani, Ankita, and Deepak Kedia. "Performance Analysis of 2-D Prime Codes Encoded Optical CDMA System." Journal of Optical Communications 40, no. 4 (October 25, 2019): 463–72. http://dx.doi.org/10.1515/joc-2017-0115.

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Abstract Optical code division multiple access (OCDMA) system provides highly secured transmission in addition to its capabilities to support asynchronous transmission and soft blocking. Two-dimensional OCDMA codes are chosen in this paper due to their high cardinality, good spectral efficiency and flexibility in their construction methods against direct sequence codes. This paper focuses on study of impact of multiple access interference (MAI) at high data rates for 2-D prime codesbased OCDMA system. It is shown that how the change in number of simultaneous users affects the transmission quality. Further, performance of the system is analysed in terms of bit error rate, received electrical power and eye openings. In addition, this paper also shows a comparative analysis of 2-D codes-based OCDMA system and wavelength division multiple access (WDMA) system in order to justify the improved performance of the proposed system. It is observed that the performance of 2-D OCDMA system is much better than WDMA system in terms of quality as well as security.

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Redouane, Berber, Bouasria Fatima, Chetioui Mohammed, Damou Mehdi, and Boudkhil Abdelhakim. "A High Performance Hybrid Two Dimensional Spectral/Spatial NZCC/MD Code for SAC-OCDMA Systems with SDD Detection." International journal of Computer Networks & Communications 14, no. 02 (March 31, 2022): 61–75. http://dx.doi.org/10.5121/ijcnc.2022.14204.

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This paper proposes a new technique to construct a hybrid zero cross-correlation (NZCC) based on multiple diagonal (MD) code for two-dimensional (2D) spectral amplitude coding for optical code division multiple access code division multiple access (SAC-OCDMA) systems. The proposed hybrid code eliminates totally the multiple access interference (MAI) between a large number of users and allows them to connect simultaneously via the optical communication link with a high speed to receive huge data and serve various areas such as Internet, telephony, DAB radio, digital audio broadcasting, and DVB video. Simulation results demonstrate that the performance of such a SAC-OCDA system based on novel 2D hybrid NZCC/MD code can be easily improved keeping a less complex structure using couplers for direct spectral/spatial dimension (SDD) detection and show superior bit error rate (BER) values comparing to previously developed two-dimensional codes including perfect difference (2D-PD), diagonal Eigen-value units (2D-DEU), multi-service (2D-MS) and balanced incomplete block design (2D-BIBD) codes.

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Yousif Ahmed, Hassan, Medien Zeghid, Waqas A.Imtiaz, Teena Sharma, Abdellah Chehri, and Paul Fortier. "Two-Dimensional Permutation Vectors’ (PV) Code for Optical Code Division Multiple Access Systems." Entropy 22, no. 5 (May 20, 2020): 576. http://dx.doi.org/10.3390/e22050576.

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In this paper, we present a new algorithm to generate two-dimensional (2D) permutation vectors’ (PV) code for incoherent optical code division multiple access (OCDMA) system to suppress multiple access interference (MAI) and system complexity. The proposed code design approach is based on wavelength-hopping time-spreading (WHTS) technique for code generation. All possible combinations of PV code sets were attained by employing all permutations of the vectors with repetition of each vector weight (W) times. Further, 2D-PV code set was constructed by combining two code sequences of the 1D-PV code. The transmitter-receiver architecture of 2D-PV code-based WHTS OCDMA system is presented. Results indicated that the 2D-PV code provides increased cardinality by eliminating phase-induced intensity noise (PIIN) effects and multiple user data can be transmitted with minimum likelihood of interference. Simulation results validated the proposed system for an agreeable bit error rate (BER) of 10−9.

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Bouarfa, Abdelkader. "Behavior study of EDEU optical code for FE-OCDMA system." Journal of Optical Communications 43, no. 2 (September 30, 2021): 281–87. http://dx.doi.org/10.1515/joc-2021-0121.

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Abstract The increase in the cardinality of the frequency encoding-optical code division multiple access (OCDMA) system directly affects the length of the optical code, which leads us to find a less expensive solution. In this work, I propose an improved version of the diagonal eigenvalue Unit code (DEU) called Enhanced diagonal eigenvalue Unit code (EDEU) that is much easier in terms of construction and short in code length compared to the DEU code. The results found showed that the performance of the EDEU code exceeds the DEU code in terms of bit error rate (BER), and allowed us to multiplex about 15 more users when using the EDEU code compared to the system using the DEU code. As a result, the EDEU code is very suitable for use in access and OCDMA systems and it can be seen as a strong competitor to existing codes.

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Matem, Rima, S. A. Aljunid, M. N Junita, C. B. M Rashidi, and Israa Shihab Aqrab. "Enhancement of optical code division multiple access system based on 2D ZCC/MD spectral/spatial code." Indonesian Journal of Electrical Engineering and Computer Science 14, no. 2 (May 1, 2019): 661. http://dx.doi.org/10.11591/ijeecs.v14.i2.pp661-667.

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<span>The combination of 1D zero cross correlation (ZCC) and 1D Multi Diagonal (MD) results a new two dimensional hybrid called 2D ZCC/MD code for spectral/spatial OCDMA system. The proposed code aims to enhance the functional qualities of Optical Code Division Multiple Access (OCDMA) and to overcome the limitations of one dimensional codes. In this paper, 2D ZCC/MD is evaluated at data rate; 622Mbps. A comparison of the proposed 2D ZCC/MD code to 1D Random Diagonal (RD) and 1D Modified Double Weight (MDW) highlight that 2D ZCC/MD can support a large number of active users even at the higher user bit rate. Furthermore, in term of effective power 2D ZCC/MD can achieve lower effective power.</span>

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Chen, Xiao Gang, Chao Jiang, Zhao Xu Liu, and De Xiu Huang. "Spectral Efficiency of Phase Encoding OCDMA Systems." Advanced Materials Research 760-762 (September 2013): 133–36. http://dx.doi.org/10.4028/www.scientific.net/amr.760-762.133.

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The spectral efficiency and bit-error-rate (BER) of phase encoding optical code division multiple access (OCDMA) systems is evaluated, coherent time-spreading (TS) and spectral phase encoding (SPE) OCDMA systems are considered. The results indicate that SPE-OCDMA has better tolerance to performance degradation due to receivers bandwidth limitation than TS-OCDMA system, while for the practical en/decoders with implementable longest code length, TS-OCDMA can yield a spectral efficiency advantage over SPE-OCDMA systems.

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Tseng, Shin-Pin, Eddy Wijanto, Po-Han Lai, and Hsu-Chih Cheng. "Bipolar Optical Code Division Multiple Access Techniques Using a Dual Electro-Optical Modulator Implemented in Free-Space Optics Communications." Sensors 20, no. 12 (June 24, 2020): 3583. http://dx.doi.org/10.3390/s20123583.

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This study developed a bipolar optical code division multiple access (Bi-OCDMA) technique based on spectral amplitude coding for the formation and transmission of optical-polarized and coded signals over wireless optical channels. Compared with conventional Bi-OCDMA schemes, the proposed free-space optics communication system that uses a dual electro-optical modulator design improves the transmission rate. In theory, multiple access interference can be removed by using correlation subtraction schemes. The experiment results revealed that the proposed system can be employed to accurately extract codewords from an M-sequence and subsequently reconstruct the desired original data. Moreover, the proposed architecture can be implemented easily in simple and cost-effective designs and may be beneficial for broadening the use of Bi-OCDMA schemes in wireless optical communications.

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Mohd Rashidi, Che Beson, S. A. Aljunid, F. Ghani, H. A. Fadhil, and M. S. Anuar. "Alleviation Interference Scheme Analysis Using Flexible Cross Correlation (FCC) Code for SAC-OCDMA Systems." Applied Mechanics and Materials 699 (November 2014): 931–36. http://dx.doi.org/10.4028/www.scientific.net/amm.699.931.

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This paper presents a new Alleviation Interference Scheme (AIS) for Spectral Amplitude Coding (SAC) - Optical Code Division Multiple Access (OCDMA) coding approaches. The AIS SAC-OCDMA systems is demonstrated by utilizing the Flexible Cross Correlation (FCC) code. The FCC code has advantages, such as flexible cross-correlation property at any given number of users and weights, as well as effectively reduces the impacts of phase induced intensity noise (PIIN) and multiple-access interference (MAI). The results indicated good performance whereas the FCC code offers 100%, 207% and 471% percentage larger number of active users compared to MDW W=4, Hadamard and MFH W=8 codes, respectively. Finally, the FCC code has low receive power Psr = -18 dBm which is expected to be more significant for future SAC-OCDMA coding systems.

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Ahmed, N., S. A. Aljunid, Hilal A. Fadil, R. B. Ahmad, and M. A. Rashid. "Hybrid OCDMA over WDM System Using Modified Double Weight (MDW) Code for Optical Access Network." Advanced Materials Research 433-440 (January 2012): 3878–83. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.3878.

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In this paper a hybrid optical code division multiple access (OCDMA) over wavelength division multiplexing (WDM) network is proposed to support large number of subscribers. The system combines two different techniques, namely OCDMA and WDM for supporting many subscribers simultaneously. We used modified double weight (MDW) codes as a signature address in designing the system because this code can accommodate more number of simultaneous active users under considerable standard bit error rate (e.g. ≤ 10-9). The induced MDW code for hybrid system can eliminate multiuser interference fully and increase the bit-error-rate performance compared to other codes at the same time. We ascertained by simulation results that the proposed scheme provides very good performance and enhance the network capability. Therefore, this system can be considered as a promising solution for the next generation optical access network.

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Yen, Chih Ta, and Wen Bin Chen. "A Study of Modified Prime Codes Optical CDMA for Wired-Wireless System." Applied Mechanics and Materials 284-287 (January 2013): 2672–76. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.2672.

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In this study, we propose optical code-division multiple-access (OCDMA) network for the radio-over-fiber (RoF) transmissions. The network encoder/decoders (codecs) are structured on the basis of arrayed-waveguide-grating (AWG) routers coded with modified prime codes (MPCs). Performances are numerically evaluated with the effect of phase-induced-intensity-noise (PIIN). It showed that the new code families with lower cross correlation can suppress the intensity noise and cancel out the multiple-access interference (MAI) in balanced detection process effectively and hence improve the system performance. By the proposed MPC-coded OCDMA ROF network codecs, each network requires only two AWG routers to accomplish spectral coding of radio base station (RBS) and decoding of control station (CS), thus, resulting in a simpler and lower cost system. It is possible to accomplish interference- and crosstalk-free optical CDMA system for RoF transmissions.

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M Mohamed, Ibrahim M., and Omlkhayr Miftah Abdulrahman. "SAC-based OCDMA codes: A comparison." ELEKTRIKA- Journal of Electrical Engineering 21, no. 1 (April 20, 2022): 20–24. http://dx.doi.org/10.11113/elektrika.v21n1.340.

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: Optical code division multiple access OCDMA is one of the promising optical access technologies due to its worth-mentioning features, such as asynchronous access, and high security. In this paper, the author performed an analytical-based comparison between three commonly used spectrum amplitude coding SAC-based OCDMA codes, namely: Modified Frequency Hopping MFH, Hadamard, and Enhanced Double Weight EDW. The comparison was made based on bit-error-rate BER observation in each case. Matlab was used to conduct this comparison. The results confirm that EDW is the best choice due to its fixed weigh. The only dilemma when adopting EDW code is how to select the proper weight.

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M Mohamed, Ibrahim M., and Omlkhayr Miftah Abdulrahman. "SAC-based OCDMA codes: A comparison." ELEKTRIKA- Journal of Electrical Engineering 21, no. 1 (April 20, 2022): 20–24. http://dx.doi.org/10.11113/elektrika.v21n1.340.

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: Optical code division multiple access OCDMA is one of the promising optical access technologies due to its worth-mentioning features, such as asynchronous access, and high security. In this paper, the author performed an analytical-based comparison between three commonly used spectrum amplitude coding SAC-based OCDMA codes, namely: Modified Frequency Hopping MFH, Hadamard, and Enhanced Double Weight EDW. The comparison was made based on bit-error-rate BER observation in each case. Matlab was used to conduct this comparison. The results confirm that EDW is the best choice due to its fixed weigh. The only dilemma when adopting EDW code is how to select the proper weight.

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Kedia, Deepak, and Ankita Rani. "Performance Evaluation of Correlation Properties of Quasi Orthogonal Prime Codes for Optical CDMA Communication." Journal of Optical Communications 41, no. 2 (March 26, 2020): 195–207. http://dx.doi.org/10.1515/joc-2017-0172.

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AbstractOptical code division multiple access (OCDMA) is one of the promising technologies to be implemented using all-optical networks. The performance of OCDMA system is largely dependent on the particular codes used for encoding. A proper choice of code family as well as code dimension is of prime importance due to various transmitter and receiver design considerations. This paper mainly aims at evaluation of desirable characteristics of various spreading codes based on the prime sequences. An extensive effort has been done in this paper to evaluate the correlation characteristics of various types of one-dimensional (1-D), 2-D and 3-D prime codes for OCDMA communication system. The detailed mathematical modelling has also been explained. It is observed that an addition in coding dimension leads to significant improvement in the code characteristics.

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Addad, Mouad, and Ali Djebbari. "A New Code Family for QS-CDMA Visible Light Communication Systems." Journal of Telecommunications and Information Technology 3 (September 28, 2018): 5–8. http://dx.doi.org/10.26636/jtit.2018.124318.

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Visible light communication (VLC) is a promising technology for wireless communication networks. Optical code division multiple access (OCDMA) is a strong candidate for VLC-based applications. The predominant source of bit error in OCDMA is the multiple access interference (MAI). To eliminate MAI in synchronous OCDMA, zero cross correlation (ZCC) codes have been proposed. However, synchronization problems and multipath propagation introduce relative non-zero time delays. Therefore, the zero correlation zone (ZCZ) concept was introduced. In this paper, we propose a new method for generating ZCC codes. The proposed construction can accommodate any number of users with ﬂexible Hamming weight. The numerical results obtained show that the proposed codes signiﬁcantly reduce MAI, compared to ZCC, as well as ZCZ codes.

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Yen, Chih Ta, and Wen Bin Chen. "A Study of Bipolar Walsh-Hadamard Coding Method in Optical CDMA Networks." Applied Mechanics and Materials 284-287 (January 2013): 2667–71. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.2667.

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This study analyzes and calculates unipolar and bipolar coded configurations of spectral-amplitude-coding optical division multiple access (SAC-OCDMA) systems by using analytic and simulated methods. The important feature of the SAC-OCDMA systems is that multiple access interference (MAI) can be eliminated by code sequences of a fixed in-phase cross-correlation value. This property can be effectively canceled by multiple access interference by using balance detection schemes. This study uses Walsh-Hadamard codes as signature codes for the unipolar and bipolar schemes. The coder and decoder structures are based on optical filters of fiber Bragg gratings (FBGs). The simulation results of unipolar/bipolar coding structures are first presented by commercial simulation obtained using OptiSystem software. The simulation results show that the bit error rate (BER) through use of the bipolar coding method is superior to the unipolar scheme, especially when the received effect power is large. The eye diagram also shows that the bipolar encoding structure exhibits a wider opening than the unipolar encoding structure.

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Cheng, Hsu-Chih, Chih-Ta Yen, and Ing-Jr Ding. "Performance Enhancement of Optical CDMA by Differential-Phase Method for Radio-over-Fiber Transmissions." Mathematical Problems in Engineering 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/901871.

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The study proposes the differential-phase optical code-division multiple-access (OCDMA) network for radio-over-fiber (RoF) transmissions, and the characteristics are numerically analyzed. The network coder/decoders (codecs) are structured on the basis of arrayed-waveguide-grating (AWG) routers with complementary Walsh-Hadamard (CWH) signature codes. In the proposed system, the network requires only two AWG routers to accomplish spectral encoding of radio base station (RBS) and decoding of control station for the complementary keying, thus resulting in a simpler and low cost system. Performance analyses are evaluated with the dominant noise of phase-induced intensity noise (PIIN) in spectral code OCDMA network. By the proposed AWG-based OCDMA with the differential-phase scheme, it is possible to establish interference-free and low crosstalk beat noise RoF systems.

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Mohd Rashidi, Che Beson, S. A. Aljunid, F. Ghani, Hilal A. Fadhil, and M. S. Anuar. "Effective Design for Fiber-to-the-Home Access Network Using Flexible Cross Correlation (FCC) Code." Key Engineering Materials 594-595 (December 2013): 1047–51. http://dx.doi.org/10.4028/www.scientific.net/kem.594-595.1047.

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This paper presented a new class of codes for Fiber-To-The-Home (FTTH) network design based on Spectral Amplitude Coding (SAC) - Optical Code Division Multiple Access (OCDMA) coding approaches. The FTTH SAC-OCDMA network is demonstrated by utilizing the Flexible Cross Correlation (FCC) code. The FCC code has an ability to suppress and cancels the effect of Multi Access Interference (MAI). The results indicated good performance whereas the FCC code offers 100%, 287% and 331% percentage larger cardinality compared to MDW W=4, MFH W=8 and Hadamard codes respectively. Finally, the FCC code accommodates low effective receive power Psr = -23dBm which is expected to be more significant for future FTTH network development for future usages.

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Li, X. B., H. B. Huang, and L. C. Wang. "Discussion on Construction of OCDMA PON Address Code-(F,K,2) Optical Orthogonal Codes." Advanced Materials Research 216 (March 2011): 804–8. http://dx.doi.org/10.4028/www.scientific.net/amr.216.804.

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Optical code division multiple access (OCDMA) passive optical network (PON) can find wide applications in the next optical access network. One of its key techniques of is construction of address code. Aiming at the facts that(F,K,1) optical orthogonal code (OOC) possesses good performance but capacity is small, and number of users in OCDMA PON is not very big thereafter OOC auto-correlation or cross-correlation may not be very strict,(F,K,2) OOC can be used as address codes for OCDMA PON. In this paper, the method of constructingOOC based on block design is discussed. The algorithm of construction (F,K,2) of OOC from block design is presented and simulated; several groups of(F,K,2) OOC are gained. The results show that the algorithm has good astringency and simplicity. It can construct(F,K,2) OOC effectively. It is feasible.

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Chowdhury, Tasnuva, and Mohammad Nasir Uddin. "OCDMA System Using Two Code Keying Encryption Introducing a SOA Based CMUX And CDEMUX Over a WDM System." AIUB Journal of Science and Engineering (AJSE) 18, no. 1 (May 31, 2019): 11–17. http://dx.doi.org/10.53799/ajse.v18i1.17.

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This paper introduces an Optical Code Division multiplexing (OCDMA) system using two code keying encryptions. In this paper proposed OCDMA system is designed using Semiconductor optical amplifiers (SOAs) which has nonlinear character and can implementor different logic functions. SOA based 2 × 1 Codeword Multiplexer (CMUX) is designed to multiplex the user data and a 1 × 2 Codeword DE Multiplexer (CDEMUX) to demodulate the user data. Then a multiple user access is provided using WDM system to design the whole OCDMA system. Transmission distance of 70 km is achieved with acceptable bit error rate and Q factor. Open eye diagram is also verified at the receiving end.

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Mamoun Kabbour, Aliaa, Hilal A. Fadhil, Angela Amphawan, Syed A. Aljunid, and Mohammad K. H. Al Mustafa. "Comparison of Single Mode Fiber and Multimode Fiber in Deployment of SCM-OCDMA in Local Area Network." Key Engineering Materials 594-595 (December 2013): 1037–40. http://dx.doi.org/10.4028/www.scientific.net/kem.594-595.1037.

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The integration of heterogeneous technologies promotes ubiquity and mobility. Optical code division multiple access (OCDMA) may be deployed in conjunction to SCM to improve the spectral efficiency and enhance the data rate of subscribers in a Local Area Network (LAN). This paper compares the performance of multimode fiber to single mode fiber in the deployment of a SCM-OCDMA system with multi-diagonal (MD) codes in a LAN.

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Alyan, Emad Ahmed, S. A. Aljunid, M. S. Anuar, and C. B. M. Rashidi. "SAC-OCDMA over Indoor Optical Wireless Communication (OWC) System Based on Zero Cross Correlation (ZCC) Code." Materials Science Forum 857 (May 2016): 603–7. http://dx.doi.org/10.4028/www.scientific.net/msf.857.603.

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This article investigates the spectral amplitude coding, optical code division multiple access (SAC-OCDMA) over indoor optical wireless communication (WO) system for various data rates and different receiver’s positions under the effect of ambient light noise. OW technology offers high speed communication with high level of security during data transmission. But it suffers from the multiple access interference (MAI) and phase induced intensity noise (PIIN) when the system associated with simultaneous multiple users. Therefore, the optical code division multiple access (OCDMA) technology is used based on zero cross correlation (ZCC) code in order to reduce those impairments that existed in OWC systems. The major advantage of ZCC code is its ability to eliminate the PIIN, thus minimize the MAI. The results show that at a bit error rate (BER) of 10-9, the system has the ability to perform at a transmission rate up to 1.2 Gbps. It also offers an excellent degree of mobility at all positions within the room at a data rate of 622 Mbps.

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Julien-Vergonjanne, Anne. "Error Probability Bound Considering Beat Noise in 2-D OCDMA Systems." Journal of Communications Software and Systems 3, no. 4 (December 20, 2007): 266. http://dx.doi.org/10.24138/jcomss.v3i4.248.

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Considering a 2-Dimensional Optical Code Division Multiple Access (2-D OCDMA) system using spreading codes in both time and wavelength domains, we study in this paper theimpact on the performance of one of the most predominantperformance limitation which is beat noise due to the photodetection. The beat noise impact is correlated with the wellknown OCDMA limitation named Multiple Access Interference (MAI). Our contribution is to assess, through a theoretical analysis, an error probability bound of a system working in incoherent or partially coherent optical regime. Thanks to the theoretical error probability expression we have developed, the specifications and requirements needed to neglect beat noise effect in a 2-D OCDMA system with a conventional receiver are easily obtained. For a targeted Bit Error Rate (BER), and a given number of active users, one can determine from our results, the 2-D code family parameters, the available data rate and the optical source characteristics, required to be free of beatnoise impact.

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Bharti, Manisha, Manoj Kumar, and Ajay K. Sharma. "A Novel Technique to Detect Code for SAC-OCDMA System." Journal of Optical Communications 39, no. 2 (April 25, 2018): 215–21. http://dx.doi.org/10.1515/joc-2016-0132.

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AbstractThe main task of optical code division multiple access (OCDMA) system is the detection of code used by a user in presence of multiple access interference (MAI). In this paper, new method of detection known as XOR subtraction detection for spectral amplitude coding OCDMA (SAC-OCDMA) based on double weight codes has been proposed and presented. As MAI is the main source of performance deterioration in OCDMA system, therefore, SAC technique is used in this paper to eliminate the effect of MAI up to a large extent. A comparative analysis is then made between the proposed scheme and other conventional detection schemes used like complimentary subtraction detection, AND subtraction detection and NAND subtraction detection. The system performance is characterized by Q-factor, BER and received optical power (ROP) with respect to input laser power and fiber length. The theoretical and simulation investigations reveal that the proposed detection technique provides better quality factor, security and received power in comparison to other conventional techniques. The wide opening of eye in case of proposed technique also proves its robustness.

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Ghanim Wadday, Ahmed Ghanim Wadday, Faris Mohammed Ali, and Hayder Jawad Mohammed Albattat. "Design of high scalability multi-subcarrier rof hybrid system based on optical CDMA/TDM." Indonesian Journal of Electrical Engineering and Computer Science 21, no. 2 (February 1, 2021): 927. http://dx.doi.org/10.11591/ijeecs.v21.i2.pp927-937.

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<span>The technology of radio over fiber (RoF) regard a crucial point to solve problems in wireless communication system. As well as, the growth of internet applications also reveals a tremendous increase in bandwidth for different applications. Therefore, the development of optical networks is very important that have maximum bandwidth by using different multiple access techniques. Optical code division multiple access (OCDMA) technique has considered as a good solution for high bandwidth network. Hybrid optical systems of OCDMA and time division multiplexing (OTDM) has been proposed in this paper to increase the number of simultaneous users. The results of hybrid OCDMA and OTDM system demonstrate that this system can make a considerable increase in the network scalability while ensuring sufficient data rate and an acceptable bit error rate. Where M-user OCDMA signals can be transmitted in different channels of an OTDM system. Due to its wide band facility compared with other access techniques, OCDMA used here. In addition to its high scalability for our radio network, the OTDM and SCM utilized. The combination of these efficient access technique and powerful time-sharing media are lead to increase the framework system scalability.</span>

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A. Memon, Kehkashan, A. W. Umrani, M. A. Unar, Wajiha Shah, and B. S. Chowdhry. "Spectral Amplitude Coding Optical CDMA: Performance Analysis on Free Space Optical Channel." International Journal of Engineering & Technology 7, no. 4.38 (December 3, 2018): 31. http://dx.doi.org/10.14419/ijet.v7i4.38.24314.

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In this paper, we investigate the performance of Spectral Amplitude Coding Optical Code Division Multiple Access technique based on Free Space Optical channel. SAC OCDMA is one of the most popular multiplexing techniques since many years and FSO is gaining popularity and is very useful especially in point to point communication. The system presented in this paper utilizes Walsh Hadamard code as signature code. The coder and decoder structures are based on optical filters of fiber Bragg gratings (FBGs). This system focuses on the performance analysis of FSO based systems for subtropical regions. This paper demonstrates the error rate performance in the form of eye diagrams/BER under varying channel gain and link distances. Five cases have been taken which shows that SAC OCDMA FSO system is reliable even for distances sufficient to overcome the last mile problem.

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Cherifi, Abdelhamid, Tarik Mohammed Chikouche, Abdullah S. Karar, Julien Moussa H. Barakat, Omar Arbouche, and Iyad Dayoub. "Capacity Improvement of 3D-OCDMA-PON Hybrid System Next Generation Using Weight Zero Cross Correlation Code." Applied Sciences 13, no. 10 (May 10, 2023): 5869. http://dx.doi.org/10.3390/app13105869.

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This paper proposes a novel code for optical code division multiple access (OCDMA) systems, called the three-dimensional (3D) spectral/temporal/spatial single weight zero cross-correlation (3D-SWZCC) code. The proposed code could potentially be used in the next generation of passive optical networks (NG-PONs) to provide a 3D-SWZCC-OCDMA-NG-PON system. The developed code has a high capacity and a zero cross-correlation property that completely suppresses the multiple access interference (MAI) effects that are a main drawback for OCDMA systems. Previously, a two-dimensional (2D) SWZCC code was proposed for two-dimensional OCDMA (2D-OCDMA) systems. It works by devoting the first and second components to spectral and spatial encodings, respectively. However, the proposed code aims to carry out encoding domains in spectral, time, and spatial aspects for the first, second, and third components, respectively. One-dimensional, 2D, and 3D systems can support up to 68, 157, and 454 active users with total code lengths equal to 68, 171, and 273, respectively. Numerical results reveal that the 3D-SWZCC code outperforms codes from previous studies, including 3D codes such as perfect difference (PD), PD/multi-diagonal (PD/MD), dynamic cyclic shift/MD (DCS/MD), and Pascal’s triangle zero cross-correlation (PTZCC), according to various metrics. The system function is provided by exhibiting the architecture of the transmitter and receiver in the PON context, where the proposed code demonstrates its effectiveness in meeting optical communication requirements based on 3D-OCDMA-PON by producing a high quality factor (Q) of 18.8 and low bit error rate (BER) of 3.48 × 10−29 over a long distance that can reach 30 Km for a data rate of 0.622 Gbps.

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ALgalbi, Wamidh. "Solving the Near-Far Problem in Dynamic Frequency Hopping-Optical Code Division Multiple Access using Power Control." Iraqi Journal for Electrical and Electronic Engineering 7, no. 2 (December 1, 2011): 88–93. http://dx.doi.org/10.37917/ijeee.7.2.1.

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In this study, a distributed power control algorithm is proposed for Dynamic Frequency Hopping Optical-CDMA (DFH-OCDMA) system. In general, the DFH-OCDMA can support higher number of simultaneous users compared to other OCDMA techniques. However, the performance of such system degrades significantly as the received power does lower than its minimum threshold. This may obviously occur in a DFH-OCDMA network with near-far problem which consist of different fiber lengths among the users, that resulting to unequal power attenuation. The power misdistribution among simultaneous active users at the star coupler would degrade the Bit Error Rate (BER) performance for users whose transmitting signals with longer fiber lengths. In order to solve these problems, we propose an adaptive distributed power control technique for DFH-OCDMA to satisfy the target Signal to oise Ratio (S R) for all users. Taking into account the noise effects of Multiple Access Interference (MAI), Phase Induced Intensity oise (PII ) and shot noise, the system can support 100% of users with power control as compared to 33% without power control when the initial transmitted power was -1dBm with 30 simultaneous users.

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Islam, Md Rabiul, Md Jahedul Islam, Bithi Mitra, Md Amzad Hossain, Jahedul Islam, and Shuvo Dev. "Performance analysis of 2D optical code division multiple access through underwater wireless optical medium." International Journal of Electrical and Computer Engineering (IJECE) 14, no. 2 (April 1, 2024): 1665. http://dx.doi.org/10.11591/ijece.v14i2.pp1665-1673.

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The performance of a two-dimensional optical code division multiple access (2D-OCDMA) system using an underwater wireless optical (UWO) medium is assessed in this work. The optical source is an LED with a working wavelength of 532 nm, and the optical detector is a p–i–n photodiode. When calculating the bit error rate (BER), the phase-induced intensity noise (PIIN), thermal noises, and shot sounds are taken into account. The user code address is set using 2D perfect difference (2D-PD) codes. Link distance, inclination angle, beam divergence angle, transmitter power, and the number of concurrent users are all taken into account when determining the BER performance. For various water media, such as pure sea water (PSW), clear ocean water (CLOW), and coastal ocean water (CSOW), the performance of the suggested system is examined.

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Chang, Yao Tang, and Chung Wei Tsailin. "Enhanced Design for AWG-Based Dynamic Reconfigurable Free-Spectral-Range Group Hopping Coder/Decoders to Protect against Eavesdropping." Applied Mechanics and Materials 764-765 (May 2015): 1240–44. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.1240.

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To further robust confidentiality protecting against eavesdropping over optical code-division multiple-access (OCDMA) networks, this study improves the robustness of the network toward eavesdropping for encryption/decryption mechanism by using a specified storage register controller controlling optical switches approach in which Free-spectral-range group hopping code is used to generate a specific signature address. This paper presents an enhanced security mechanism to protect spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) networks against eavesdropping. This study proposes an alternative to huge code-space size techniques such as wavelength hopping and exchange-encode for network protection against eavesdropping by exploiting the cyclic properties of arrayed-waveguide-grating routers and maximal-length sequence code (M-sequence code). In addition, the network is protected using a wavelength hopping based on optical switches and exchange the encode assignment scheme implemented using the exchange switches before import to arrayed-waveguide-grating routers (AWG).In this scheme, eavesdropper is difficult to solute correct user data bit , whatever there is using brute-force searching or simple energy detector..

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Chen, Kai-Sheng. "Multiple-Code Technique for Multi-Rate Transmissions in Optical Packet Switching Networks Based on OCDMA Labels." Photonics 6, no. 2 (May 30, 2019): 60. http://dx.doi.org/10.3390/photonics6020060.

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Supporting multi-rate transmission is an essential factor in current optical packet switching (OPS) networks. In this paper, the author studied a multi-rate scheme capable of forwarding packets with different signal rates based on label switching. The multiple-code (MC) technique was employed to label a packet by conveying its payload bits to multiple optical code-division multiple-access (OCDMA) labels. Spectral-amplitude-coding (SAC), which represents the chips in an OCDMA code as a set of wavelengths, was introduced to remove the multiple-access interference (MAI) from the overlapping among labels. The author tested the system effectiveness by conducting numerical analysis to formulate bit-error probability (BEP) and spectral efficiency (SE). The simulation results showed that the proposed network had a stable BEP performance when switching the packet flows of multiple data-rates.

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Li, Chuan Qi, Zhi Guo Shen, Hui Chen, and Xu Zhou. "A SOA-Based Scheme for MAI Suppression in OCDMA." Advanced Materials Research 403-408 (November 2011): 2196–99. http://dx.doi.org/10.4028/www.scientific.net/amr.403-408.2196.

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A noise suppression scheme based on semiconductor optical amplifier (SOA) is investigated in this paper. It aims to inhibit the Multiple-Access interference (MAI) which is the major noise in incoherent optical code division multiple access (OCDMA) system. The saturated SOA is employed as optical limiting amplifier here. The performance of proposed MAI suppression system is analyzed theoretically and experimentally.

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Matem, Rima, S. A. Aljunid, M. N. Junita, C. B. M. Rashidi, and Israa Shihab Aqrab. "Performance analysis of spectral/spatial of OCDMA system using 2D hybrid ZCC/MD code." Indonesian Journal of Electrical Engineering and Computer Science 13, no. 2 (February 1, 2019): 569. http://dx.doi.org/10.11591/ijeecs.v13.i2.pp569-574.

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This paper proposes a new spectral/spatial code for Spectral Amplitude Coding in Optical Coding Division Multiple Access (SAC-OCDMA) called two-Dimensional hybrid ZCC/MD code. The new code combines two of the one –dimensional codes which are Zero Cross Correlation (1D ZCC) and Multi-Diagonal code (1D MD). Moreover, it produces a zero cross correlation property for each code. The main goal of this proposed code is to mitigate Phase Induced Intensity Noise and eliminate Multiple Access Interference (MAI). This proposed code can provide a better performance comparing to other codes as 2D FCC/MDW and 2D DPDC according to the obtained numerical analysis.

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Yen, Chih-Ta, Ing-Jr Ding, and Cheng-Mu Tsai. "PERFORMANCE ANALYSIS OF SEVERAL QUASI-ORTHOGONAL CODES OPTICAL CDMA FOR RADIO-OVER-FIBER SYSTEM." Transactions of the Canadian Society for Mechanical Engineering 37, no. 3 (September 2013): 415–26. http://dx.doi.org/10.1139/tcsme-2013-0031.

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An optical code-division multiple-access (OCDMA) network for radio-over-fiber (RoF) transmissions was proposed. The network encoders/decoders (codecs) were structured based on arrayed-waveguide-grating (AWG) routers coded using modified prime codes (MPCs). In the proposed system, the lower in-phase cross correlation could reduce the beating noise, and in the proposed study, its performance was compared with that of a conventional system that uses M-sequence and Walsh-Hadamard codes. The performance of both systems was numerically evaluated by analyzing the effect of phase-induced-intensity noise (PIIN). The results showed that the new code families that had lower cross correlation can suppress the intensity of the noise and effectively cancel out the multiple-access interference (MAI) in balanced detection processes, which improved system performance. By using the proposed MPC-coded OCDMA ROF network codecs, each network required only two AWG routers to accomplish the spectral coding of radio base stations (RBSs) and the decoding of control stations (CSs), resulting in a simple and low-cost system. Therefore, it is possible to produce interference- and crosstalk-free optical CDMA systems for RoF transmissions.

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37

Mrabet, Hichem. "A Performance Analysis of a Hybrid OCDMA-PON Configuration Based on IM/DD Fast-OFDM Technique for Access Network." Applied Sciences 10, no. 21 (October 30, 2020): 7690. http://dx.doi.org/10.3390/app10217690.

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The purpose of this article is to propose a new configuration based on OCDMA and Fast-OFDM techniques for access network applications. A hybrid intensity modulation with direct detection, fast orthogonal frequency-division multiplexing–code division multiplexing access (IM/DD Fast-OFDM-CDMA) system is analytically and numerically evaluated for an amplifier-free access network. Therefore, system performance is analytically investigated in terms of bit error rate/Q-factor as a function of simultaneous users, fiber length and launched optical power. Firstly, the proposed analytical model includes the overlapping effect among OFDM subcarriers, the peak-to-average power ratio (PAPR), and multiple access interference (MAI). Secondly, a simulation setup is performed, allowing four simultaneous users operating at 40 Gb/s in a passive optical network (PON) context. Furthermore, a power budget analysis is made between IM/DD Fast-OFDM-CDMA, all-optical IM/DD OFDM-CDMA (IM/DD AO-OFDM-CDMA) and OCDMA wavelength division multiplexing (OCDMA-WDM) configurations. It is shown that at 40 Gb/s and by using 2D-hybrid coding (2D-HC), the maximum achievable transmission-reach of IM/DD Fast-OFDM-CDMA is 142 km, which is 34 km and 60 km higher than those provided by the IM/DD AO-OFDM-OCDMA and OCDMA-WDM PON configurations, respectively.

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Rani, Monika, Harbax Singh Bhatti, and Vikramjeet Singh. "Performance Analysis of Spectral Amplitude Coding Optical Code Division Multiple Access System using Modified Double Weight Codes with Adomian Decomposition Method." Journal of Optical Communications 39, no. 4 (October 25, 2018): 459–62. http://dx.doi.org/10.1515/joc-2017-0028.

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Abstract In this manuscript, we have analyzed a Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) System. The system performance is enhanced by reducing the effect of Multiple Access Interference (MAI) using uniform Fiber Bragg Gratings (FBGs) encoders and decoders at central office and subscriber’s end. The results are verified through a mathematical model and Modified Double Weight (MDW) codes for the proposed system using Adomian Decomposition Method (ADM). Further, we have demonstrated SAC-OCDMA system for transmission of 40 Gbps data rate up to a distance of 80 km by increasing the number of FBGs. The proposed system has been analyzed in terms of distance, bit error rate (BER) and Quality Factor.

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Yen, Chih Ta, and Chia Yu Liu. "Hybrid Analog/Digital Modulations Using Polarization Multiplexing OCDMA Scheme in Free Space Optics." Applied Mechanics and Materials 764-765 (May 2015): 511–14. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.511.

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With the development of the Internet, how to provide a high-speed and high-security comprehensive network has become urgent issue. In this project, we propose hybrid analog/digital transmissions format scheme which integrated optical code-division multiple-access (OCDMA) and polarization multiplexing technique in free space optics (FSO) transmission. Orthogonal frequency division multiplexing (OFDM) transmits as the analog format and (on-off keying) OOK transmits as digital format in the study, respectively. In the proposed hybrid OCDMA system, it has high-speed transmission, signal security and low cost...etc. we adopt quasi-orthogonal Walsh-Hadamard codes (WHC) that with fixed cross correlation value as the codeword for each base station. With the property, the multiple access interference (MAI) can be efficiently eliminated by using the balanced detection scheme at the receive end. The constellation and eye diagrams show that both OFDM signal as analog signal and OOK modulation as digital signal in the proposed hybrid OCDMA system perform good performance in FSO transmission.

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Yen, Chih-Ta, and Chih-Ming Chen. "BER Analysis Using Beat Probability Method of 3D Optical CDMA Networks with Double Balanced Detection." Mathematical Problems in Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/456829.

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This study proposes novel three-dimensional (3D) matrices of wavelength/time/spatial code for code-division multiple-access (OCDMA) networks, with a double balanced detection mechanism. We construct 3D carrier-hopping prime/modified prime (CHP/MP) codes by extending a two-dimensional (2D) CHP code integrated with a one-dimensional (1D) MP code. The corresponding coder/decoder pairs were based on fiber Bragg gratings (FBGs) and tunable optical delay lines integrated with splitters/combiners. System performance was enhanced by the low cross correlation properties of the 3D code designed to avoid the beat noise phenomenon. The CHP/MP code cardinality increased significantly compared to the CHP code under the same bit error rate (BER). The results indicate that the 3D code method can enhance system performance because both the beating terms and multiple-access interference (MAI) were reduced by the double balanced detection mechanism. Additionally, the optical component can also be relaxed for high transmission scenery.

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Plascencia, Emmanuel, Oyunchimeg Shagdar, Hongyu Guan, Olivier Barrois, and Luc Chassagne. "Optical CDMA MAC Evaluation in Vehicle-to-Vehicle Visible Light Communications." Electronics 11, no. 9 (April 30, 2022): 1454. http://dx.doi.org/10.3390/electronics11091454.

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One of the most critical challenges in vehicle-to-vehicle (V2V) visible light communications (VLCs) is the access capability of multi-users over the same channel. VLC links are known to be line of sight (LOS) and highly directional compared to the commonly used radio-frequency (RF) technologies, but multi-user interference can still be problematic. Consequently, it is necessary to develop a medium access control (MAC) protocol for VLC. In the present work, we propose a novel optical code division multiple access (OCDMA) protocol. The fundamentals of the VLC channel are presented, and the interference problem is discussed in more detail. We also explain the CDMA MAC protocol and its adaptation from optical fiber communications. The simulations with our OCDMA protocol based on pseudo-noise (PN) sequence codes are presented, and the results are compared with those obtained using a solution based on VLC and optical orthogonal codes (OOCs) from the OCDMA gold standard. Finally, the results show that PN sequence OCDMA can provide sufficiently high performance and is particularly attractive because there are no synchronization requirements between nodes in real V2V scenarios.

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Jabar, Hashem A., and Rashid A. Fayadh. "Implement Algorithm to Reduce Effect of Snowy Weather in North of Iraq on Fso Signal." Science Journal of University of Zakho 6, no. 3 (September 30, 2018): 130–34. http://dx.doi.org/10.25271/sjuoz.2018.6.3.520.

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Free space optic (FSO) is now a well-established access technology that commonly start using in wireless data transmission because of its large advantage like cost effective and Line-Of-Sight (LOS) permission which lead this technology to be more secure and get own to everyone. While radio frequency (RF) travels using optical fiber through weather atmospheric, large phenomena like (Rain-fog/haze-snow and temperature) works to block laser beam from reaching its receiver. Optical code division multiple access (OCDMA) is a hot topic due to its large advantage such as permitting large number of user to transmit large amount of data using single optical laser beam , but multiple users share single laser beam lead to increase multiple access interference (MAI) which primary deteriorates the performance of OCDMA. Sub-Carrier Multiplexing (SCM) is used in the system to multiplex multiple data stream on single laser beam. Spectral Amplitude Coding (SAC) technique used to enhance FSO signal by allocate own spectrum to each user, this technique generate code called Multi-Diagonal (MD) code that allow zero interaction between user data. This paper focused on the effect of snowy weather in north of Iraq on the FSO signal by using (SCM-SAC-OCDMA) based on multi-diagonal code and determined the distance between the transverse with approach bit error rate (BER) in the receiver side. Based on the system result data can travel through [0.4 - 4] Km as transmission distance under different snow rate with BER between [].

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Amaseb, Kamal Elsiddig, Hassan Yousif Ahmed, and Medien Zeghid. "An Efficient Method to Reduce an MAI’s Effect in Spectral Amplitude Coding OCDMA Network." European Journal of Engineering Research and Science 2, no. 6 (June 1, 2017): 1. http://dx.doi.org/10.24018/ejers.2017.2.6.339.

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Multiple access interference (MAI) in spectral-amplitude coding, optical code division multiple access (SAC-OCDMA) scheme hardly limits the system performance. This problem increases proportionally with the amount of concurrent users. In addition, phase induces intensity noise (PIIN) coming from the spontaneous emission process of light source is extra impairment leads to system drop needs to be tackled too. Towards overcome the specified problems, vector combinatorial (VC) codes which based on grouping of certain vectors is proposed. Any positive integer number can be used in both weighs and user parameters in code building procedure, these technique nominees our code to be a potential reliable applicant for future optical communication schemes. Such flexibility is an exceptional property for VC compared to SAC-OCDMA counterparts’ codes. Compared with the systems employing Hadamard, Modified Frequency Hopping (MFH), Modified Quadratic-Congruence (MQC), and Modified Double Weight (MDW), numerical results show that, the VC is effective to reduce the power of MAI and PIIN. It has been exposed that, performance can be superior significantly when VC is used.

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Amaseb, Kamal Elsiddig, Hassan Yousif Ahmed, and Medien Zeghid. "An Efficient Method to Reduce an MAI’s Effect in Spectral Amplitude Coding OCDMA Network." European Journal of Engineering and Technology Research 2, no. 6 (June 1, 2017): 1–6. http://dx.doi.org/10.24018/ejeng.2017.2.6.339.

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Multiple access interference (MAI) in spectral-amplitude coding, optical code division multiple access (SAC-OCDMA) scheme hardly limits the system performance. This problem increases proportionally with the amount of concurrent users. In addition, phase induces intensity noise (PIIN) coming from the spontaneous emission process of light source is extra impairment leads to system drop needs to be tackled too. Towards overcome the specified problems, vector combinatorial (VC) codes which based on grouping of certain vectors is proposed. Any positive integer number can be used in both weighs and user parameters in code building procedure, these technique nominees our code to be a potential reliable applicant for future optical communication schemes. Such flexibility is an exceptional property for VC compared to SAC-OCDMA counterparts’ codes. Compared with the systems employing Hadamard, Modified Frequency Hopping (MFH), Modified Quadratic-Congruence (MQC), and Modified Double Weight (MDW), numerical results show that, the VC is effective to reduce the power of MAI and PIIN. It has been exposed that, performance can be superior significantly when VC is used.

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Morsy, Morsy A., and Moustafa H. Aly. "A New Hybrid Prime Code for OCDMA Network Multimedia Applications." Electronics 10, no. 21 (November 5, 2021): 2705. http://dx.doi.org/10.3390/electronics10212705.

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This paper presents a new family of spreading code sequences called hybrid prime code (HPC), to be used as source code for the optical code division multiple access (OCDMA) network for large network capacity. The network capacity directly depends on the number of available code sequences provided and their correlation properties. Therefore, the proposed HPC is designed based on combining two or more different code words belonging to two or more different prime numbers. This increases the number of code sequences generated. The code construction method utilized allows the generation of different code sets, each with different code length and weight, according to the number of prime numbers used. In addition, the incoherent pulse position modulation (PPM) OCDMA system is proposed based on the HPC code. Furthermore, the bit error rate (BER) performance analysis is introduced versus the received optical power and the number of active users. Moreover, the error vector magnitude (EVM) is calculated versus the optical signal-to-noise ratio. This work proves that using two prime numbers simultaneously generates far more codes than using prime numbers separately. It also achieved an OCDMA system capacity higher than the system that uses the optical orthogonal codes (OOCs), modified prime codes (MPCs) families, and two code families with separate simultaneously prime numbers, at a BER below 10−9 which is the optimum level.

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Seyedzadeh, Saleh, Andrew Agapiou, Majid Moghaddasi, Milan Dado, and Ivan Glesk. "WON-OCDMA System Based on MW-ZCC Codes for Applications in Optical Wireless Sensor Networks." Sensors 21, no. 2 (January 13, 2021): 539. http://dx.doi.org/10.3390/s21020539.

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The growing demand for extensive and reliable structural health monitoring resulted in the development of advanced optical sensing systems (OSS) that in conjunction with wireless optical networks (WON) are capable of extending the reach of optical sensing to places where fibre provision is not feasible. To support this effort, the paper proposes a new type of a variable weight code called multiweight zero cross-correlation (MW-ZCC) code for its application in wireless optical networks based optical code division multiple access (WON-OCDMA). The code provides improved quality of service (QoS) and better support for simultaneous transmission of video surveillance, comms and sensor data by reducing the impact of multiple access interference (MAI). The MW-ZCC code’s power of two code-weight properties provide enhanced support for the needed service differentiation provisioning. The performance of this novel code has been studied by simulations. This investigation revealed that for a minimum allowable bit error rate of 10−3, 10−9 and 10−12 when supporting triple-play services (sensing, datacomms and video surveillance, respectively), the proposed WON-OCDMA using MW-ZCC codes could support up to 32 simultaneous services over transmission distances up to 32 km in the presence of moderate atmospheric turbulence.

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Wijanto, Eddy. "Performance Analysis of Bipolar Optical Code Division Multiple Access with Dual Electro-Optical Modulator Scheme for Free-Space Optical Communication." Techné : Jurnal Ilmiah Elektroteknika 20, no. 2 (October 2, 2021): 67–82. http://dx.doi.org/10.31358/techne.v20i2.270.

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In this study, the performance of bipolar optical code division multiple access (OCDMA) with dual electro-optical modulator (EOM) scheme for multi-user scenario was tested and analyzed with OptiSystem version 10. The performance measurement was implemented for free-space optical (FSO) communication and includes the common noises in optical communication. Two different channels were used in the measurement, i.e., additive white Gaussian noise (AWGN) and fading channel. Two extreme weather conditions, strong rain and storm, were considered in the simulation. The performance between three spectral amplitude coding (SAC) codes, i.e., Modified M-Sequence code, Walsh-Hadamard code, and random diagonal (RD) code were measured and compared. The simulation results indicate that Modified M-Sequence code had the highest BER while RD code achieved the lowest BER in the short-range and Walsh-Hadamard code got the lowest BER for the medium-range of FSO, both for AWGN only and AWGN with fading channel. In strong turbulence condition, the performance of all codes become comparable after 500 m of FSO range. Modified M-Sequence suffered the lowest performance degradation while RD code endured the highest performance deterioration in all-weather condition. The results show that Modified M-Sequence can be applied for medium to long-range FSO.

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Kim, Gunzung, and Yongwan Park. "Suitable Combination of Direct Intensity Modulation and Spreading Sequence for LIDAR with Pulse Coding." Sensors 18, no. 12 (November 30, 2018): 4201. http://dx.doi.org/10.3390/s18124201.

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In the coded pulse scanning light detection and ranging (LIDAR) system, the number of laser pulses used at a given measurement point changes depending on the modulation and the method of spreading used in optical code-division multiple access (OCDMA). The number of laser pulses determines the pulse width, output power, and duration of the pulse transmission of a measurement point. These parameters determine the maximum measurement distance of the LIDAR and the number of measurement points that can be employed per second. In this paper, we suggest possible combinations of modulation and spreading technology that can be used for OCDMA, evaluate their performance and characteristics, and study optimal combinations according to varying operating environments.

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Chen, Kai-Sheng. "Packet Switching Strategy and Node Architecture of Extended Spectral-Amplitude-Coding Labels in GMPLS Networks." Applied Sciences 9, no. 7 (April 11, 2019): 1513. http://dx.doi.org/10.3390/app9071513.

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We present packet switching applications based on extended spectral-amplitude-coding (SAC) labels in generalized multi-protocol label switching (GMPLS) networks. The proposed approach combines the advantages of wavelength-division multiplexing (WDM) and optical code-division multiple access (OCDMA). The extended SAC labels preserve the orthogonal property to avoid the effect of multiple access interference (MAI) shown at the decoder. We investigate the node architecture of label generation/recognition based on arrayed waveguide grating (AWG). Combining cyclic-shifted maximal length sequence (MLS) codes with the wavelength routed property of AWG simplifies the node structure. The simulation results show that the proposed labels achieve good performances against receiver noise due to the low average cross-correlation values. Under a given bit-error-rate (BER), the switching efficiency of the extended SAC labels outperforms the previous OCDMA schemes, as the network nodes are capable of processing a large number of labels simultaneously.

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Islam, A. K. M. Nazrul, and Satya Prasad Majumder. "Bit Error Rate Performance in CDMA Free Space Optical Links with SIK Receiver under Fog Conditions." MIST INTERNATIONAL JOURNAL OF SCIENCE AND TECHNOLOGY 11 (December 28, 2023): 81–86. http://dx.doi.org/10.47981/j.mijst.11(02)2023.409(81-86).

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This article presents a novel analytical method for evaluating fog's impact on Bit Error Rate (BER) in an Optical Code Division Multiple Access (OCDMA) Free Space Optical (FSO) connection. The investigation employs an optical encoder and direct detection receiver employing a balanced photo detector with Sequence Inverse Keying (SIK) to explore fog effects. By scrutinizing multi-access interference (MAI) current and signal current values at the SIK receiver's output under varied fog conditions, we deduce BER expressions for diverse scenarios. These encompass different fog thickness levels, code lengths, simultaneous users, and system parameters. The results reveal substantial OCDMA degradation due to fog thickness and users. Also, the system incurs a marked power penalty at a specific BER, especially with higher fog and user density. However, we identify a potential solution: increasing code length, effectively mitigating fog-induced performance decline.

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Journal articles on the topic 'Optical code division multiple access (OCDMA)'

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